STATEN ISLAND, N.Y. -- For the first time in city history, residents of flood-prone, low-lying areas across the five boroughs, including tens of thousands in Midland Beach, South Beach and Ocean Breeze, were ordered to evacuate today.

In another unprecedented move, Staten Island University Hospital (SIUH) was also evacuated today.

Residents have until 5 p.m. tomorrow to get out of the "Zone A," areas on the East Shore and elsewhere around the Island.

Residents have been told that they shouldn't expect to be back in their homes until 9 p.m. Sunday at the earliest.

Miley said he packed his medications, water, flashlights and other necessities last night in anticipation of the evacuation.

Rina Svet and her brother Greg were unloading bottled water and other groceries from their car in Ocean Breeze.

"This is crazy," Ms. Svet said. "I'm going to Queens with my boyfriend and my parents are going to Brooklyn."

Jennifer Shavnessy, also of Ocean Breeze, was taking potted plants and patio furniture inside before she reluctantly evacuated.

"I really don't want to go," she said. "If it were up to me I'd stay and make them kick me out."

In ordering the evacuations, Mayor Michael Bloomberg said that Midland Beach and other Island areas will be among the hardest hit in the city by the storm surge.

"I can't stress it enough," Bloomberg said, "nature is a force more powerful than any of us, and it really is better to be safe than sorry."

The zone includes Islanders along all four shores and also goes into communities like Tottenville, Prince's Bay, Travis and St. George.

Borough President James P. Molinaro said he may have staffers drive down streets in the flood zones with bullhorns in order to tell people to leave.

The city opened evacuation centers across the city, including five on the Island, this afternoon.

As food and supply trucks dropped off goods at one of them, Curtis High School, volunteers labeled the wrought-iron fences outside the school with signs reading, "Shelter" and arrows directing evacuees toward building's main entrance.

Curtis opened its doors as a public evacuation site at 4 p.m. today.

The 650-person capacity lunchroom will be the first portion of Curtis to house people. If the room fills, other parts of the building will be used.

"As many as we can take," said a person at the school. "We're here if needed."

In a bid to get ahead of the storm, the city Department of Environmental Protection today cleared out stormwater catch basins in low-lying areas across the city, including here.

The agency said that crews will be out again tomorrow if all the basins haven't been cleaned.

For some in sensitive locations, the evacuations began even earlier.

For the first time in 150 years, Staten Island University Hospital (SIUH) temporarily closed its doors today after it was ordered to evacuate the 360 patients from its Ocean Breeze and Pleasant Plains sites.

The facilities are also in Zone A and were expected to be emptied by tomorrow morning.

Anthony Ferreri, president and CEO of SIUH assured residents that both hospital sites will have staff on hand throughout the storm to assist with emergencies.

"Our concern is that patients would be in jeopardy, and it would be safer for the patients and their well-being if we were to transport them to other facilities," Ferreri said.

Patients were moved by ambulance or MTA bus, depending on their conditions. They were sent to some of the other 15 hospitals in the North Shore-LIJ Health System.

SIUH officials said there had been four practice hospital evacuations over the last four years.

Evacuations also took place today at three health-care or residential facilities in South Beach.

Around 325 patients and more than 100 staffers from South Beach Psychiatric Facility were moved via chartered bus to Creedmoor Psychiatric Center in Queens, said deputy director Dr. Thomas Uttaro.

The facility's safety department will remain on site and South Beach's emergency command center will remain open.

All 160 residents of New Broadview Manor Home for Adults and Assisted Living Facility on Capodanno Boulevard were also evacuated, and were sent to other Island facilities.

Assistant administrator Amy Murnane said that the residents are being sent with medication, blankets, pillows, diapers, canned goods and three days' worth of clothes.

"We hope they're back by Sunday night," she said. "But we'll see what Irene has in mind."

The Island Shores Senior Residence, also on Capodanno, made arrangements for its 90 residents to either stay with family members or at borough hotels.

Other nursing homes and facilities that were not ordered evacuated still battened down the hatches.

Laura Saccone, director of staff development at Carmel Richmond Healthcare and Rehabilitation Center, Dongan Hills, said the facility has enacted is "disaster preparation" plan.

The home has laid in extra food, linens and other supplies, and is also planning ways to pick up staffers who may not be able to make it into work over the weekend.

She said the home is also accepting patients from SIUH.

"We're as prepared as we can be," said Ms. Saccone. "We feel pretty good."

JCPenney boarded up the windows with plywood at its Staten Island Mall location today. It was not known if the storm would curtail store hours at the Mall overall.

The Mall set up a "weather update" link on its website so shoppers could check.